1. Field of the Invention
The present invention relates generally to optical scanner devices and, more particularly to a cost effective and functionally efficient optics module and scan window for an optical scanner device.
2. Description of the Related Art
Optical scanners are well-known in the art to produce machine-readable data that can represent an image contained on an object, e.g. a page of printed text. In general, the data is obtained from an optics module reflecting a beam of light off of a xe2x80x9cscan linexe2x80x9d region of the object being scanned. When an optics module is used in a portable scanner, the reflected beam of light is obtained as the user physically moves the optical scanner across the object with their hand. Consequently, the optics module for hand-held or portable scanning devices must generally be very compact and often employ a navigational assembly to track and associate what portion of the object has been scanned.
Referring to FIG. 1, the basic components of a portable scanner are shown. The scanner 5 includes an optics module 10 having a scanning assembly 12 and a navigational assembly 14 coupled to an image processing system 30. With each assembly, an illumination device 16, such as one or more LED""s, creates a beam of light 18A, 18B that passes through the scanner casing 20 at a scan window 22A, 22B having a transparent material 32. Next, the beam of light 18A, 18B reflects off of the surface of the object 24 being scanned before reflecting back through the scan window 22A, 22B. The reflected beam of light 18Axe2x80x2, 18Bxe2x80x2 is focused by a lens 26 and received by an illumination sensor or photosensor 28.
The photosensor 28 works with other electronic components 30 to evaluate and translate the reflected beam of light 18Axe2x80x2, 18Bxe2x80x2 into an electronic copy of the image contained by the object 24. The electronic components 30 could include a microprocessor, memory and related translational software that is contained by the scanner or by a personal computer being accessable by a data cable.
With the conventional optics modules described above, the illumination source 16 radiates light over a full hemisphere, so only a small portion of the light is directed toward the scan region, and the light flux per unit angle is relatively low. Consequently, if the illumination source 16 is tilted or moved slightly away from the object 24, the illumination level through the scan window 22A and 22B at the scan line falls rapidly, resulting in an undesirably dark image or a very non-uniform image to be captured by the photosensor 28.
The transparent material 32 is made from plastic or glass and functions as a seal in the casing so that the optical and electronic components contained therein can be protected from dust, moisture and other potential contaminants that could possibly damage the operation of the scanner. The transparent material provides optical losses due to surface reflections and internal transmissions. In particular, each time a beam of light 18A or 18Axe2x80x2 passes through the transparent material, the beam of light is diminished by about 8%. An anti-reflective coating may be applied to the transparent material to reduce the optical losses, however this will only reduce the optical loss to about 1.5%.
FIG. 2 illustrates a cross-sectional view of how the transparent material 32 may be secured to the scanner casing 20. In particular, FIG. 2 shows how the casing 20 can be manufactured to provide a scan window 22A, 22B that includes a ledge for supporting the transparent material 32 with an adhesive 36. With this structure, the transparent material 32 is positioned a depth xe2x80x9cdxe2x80x9d, between 0.02-0.05 mm, away from an outer surface 38 of the casing 20 to create a recessed border defined by square comer regions 40.
The recessed border is not deep enough to prevent a staple or a hard particle contained on an object from scratching the transparent material while the object is being scanned. In addition, the square comer regions 40 collect dust and other contaminants in areas that are hard to clean. Consequently, the scratches and collected contaminants further increase optical losses in the operational scanner. In turn, such optical losses may force the user to have the manufacturer replace the transparent material, which is not only time consuming, but costly. Lastly, the square comer regions 40 may cause the comers of the object being scanned to become jammed along the recessed borders of the scan window during the scanning process.
Thus, it would be desirable to provide an apparatus that overcomes the above problems associated with an optics module and scan window for a scanning devices.
In one embodiment, the present invention provides an optical scanner having a casing. The casing includes a scan window, a substrate attached within the casing and being laterally spaced from the scan window, and an optics module coupled between the scan window and the substrate to form a recess within the casing.
In another embodiment, the present invention provides a method for manufacturing a recessed scan window for use in an optical scanning apparatus having a casing. The method includes: forming a contact window within a scan surface of the apparatus casing; securing a substrate within the apparatus casing; coupling a first end of an illumination device to the substrate and a second end adjacent to a first portion of the contact window; and coupling a first end of a photosensor component to the substrate and a second end adjacent to a second portion of the contact window, wherein the second end of the illumination device and the photosensor component forms the recessed scan window.